The functions of cells in biological systems are guided by the spatial and temporal delivery of a range of chemical and mechanical cues. A wide variety of engineered materials have been investigated with the goal of exerting control over cell behaviors such as adhesion to surfaces, differentiation, and proliferation in in vitro and biomedical applications. The interactions of cells with solid surfaces, for example, have been engineered by controlling surface chemistry, topographical features, compliance of the substrate, and combinations of these parameters. Synthetic materials have also formed the basis of approaches that measure the interactions between cells and their environments. For example, certain approaches have previously been described that use microfabricated elastomeric posts to measure the patterns of mechanical forces exerted by cells on surfaces.
The liquid crystalline state is widely encountered in biological systems. For example, the membranes of cells are liquid crystalline, and concentrated solutions of biomolecules such as DNA and proteins are known to form liquid crystals. In light of this, it is surprising that few studies aimed at engineering synthetic materials to interact with live cells have explored the use of synthetic liquid crystals. Past studies have investigated the orientations of the nematic liquid crystal 4′-pentyl-4-cyanobiphenyl (5CB) on cells attached to surfaces. These cells, however, were fixed (i.e., dead) and the liquid crystal used in their investigation (5CB) has subsequently been shown to cause cell death when contacted with live cells for short periods of time. In a separate study, Luk and coworkers surveyed liquid crystalline materials containing a variety of functional groups and found several liquid crystals that were non-toxic to live mammalian cells. In particular, fluorinated liquid crystals exhibited minimal toxicity toward 3T3 fibroblasts and corneal epithelial cells.
Accordingly, there exists a need in the field to engineer synthetic materials that, in a first aspect, offer a suitable culture substrate for living cells and, in a second aspect, provide means to monitor cell behaviors such as adhesion to surfaces, differentiation, and proliferation.